Method of forming a porous multilayer material

Abstract

Forming a porous multilayer material includes forming a multilayer material on a substrate. Forming the multilayer material includes alternately forming a sacrificial layer and a semi-sacrificial layer, where the sacrificial layer includes a first metal and the semi-sacrificial layer includes the first metal and a second metal or metallic alloy. Forming the porous multilayer material further includes removing at least a portion of the first metal from each of the sacrificial and semi-sacrificial layers to yield the porous multilayer material. The porous multilayer material includes a multiplicity of metal-containing layers, each layer having a thickness in a range between about 5 nm and about 100 nm and bonded to an adjacent layer. Each layer includes chromium, niobium, tantalum, vanadium, molybdenum, tungsten, or a combination thereof. A void is defined between each pair of layers, and a density of porous the multilayer material is <1% bulk density.

What is claimed is: 
     
       1. A method of forming a porous multilayer material, the method comprising:
 forming a multilayer material on a substrate, wherein forming the multilayer material comprises alternately forming a sacrificial layer and a semi-sacrificial layer, wherein the sacrificial layer comprises a first metal and the semi-sacrificial layer comprises the first metal and a second metal or metallic alloy; 
 separating the multilayer material from the substrate; and 
 removing at least a portion of the first metal from each of the sacrificial and semi-sacrificial layers to yield the porous multilayer material. 
 
     
     
       2. The method of  claim 1 , further comprising sintering the porous multilayer material to bond each semi-sacrificial layer to an adjacent semi-sacrificial layer. 
     
     
       3. The method of  claim 1 , further comprising, after removing at least the portion of the first metal, sintering the porous multilayer material to bond each semi-sacrificial layer to an adjacent semi-sacrificial layer. 
     
     
       4. The method of  claim 3 , further comprising crushing the porous multilayer material. 
     
     
       5. The method of  claim 1 , wherein forming the sacrificial layer comprises electron beam evaporation of the first metal. 
     
     
       6. The method of  claim 1 , wherein forming the semi-sacrificial layer comprises sputtering. 
     
     
       7. The method of  claim 1 , wherein removing at least the portion of the first metal comprises dissolving at least the portion of the first metal. 
     
     
       8. The method of  claim 1 , wherein removing at least the portion of the first metal comprises boiling off at least the portion of the first metal. 
     
     
       9. The method of  claim 1 , wherein removing at least the portion of the first metal comprises removing substantially all of the first metal. 
     
     
       10. The method of  claim 1 , wherein removing at least the portion of the first metal defines voids between the semi-sacrificial layers. 
     
     
       11. The method of  claim 1 , wherein a thickness of each sacrificial layer is in a range of about 0.2 μm to about 2 μm. 
     
     
       12. The method of  claim 1 , wherein a thickness of each semi-sacrificial layer is in range of about 5 nm to about 100 nm. 
     
     
       13. The method of  claim 1 , wherein a thickness of the porous multilayer material is in a range of about 100 μm to about 500 μm. 
     
     
       14. The method of  claim 1 , wherein the first metal comprises one or both of copper and magnesium. 
     
     
       15. The method of  claim 1 , wherein the second metal or metallic alloy comprises one or more of chromium, niobium, tantalum, vanadium, molybdenum, and tungsten. 
     
     
       16. The method of  claim 1 , wherein each semi-sacrificial layer comprises 70-85 atomic percent of the first metal.